| Message ID | 4327888.LvFx2qVVIh@kreacher |
|---|---|
| State | New |
| Headers | show |
| Series | [RFT] PCI: Use pci_update_current_state() in pci_enable_device_flags() | expand |
On Thu, Jul 8, 2021 at 10:34 PM Maximilian Luz <luzmaximilian@gmail.com> wrote: > > On 7/8/21 3:25 PM, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > Updating the current_state field of struct pci_dev the way it is done > > in pci_enable_device_flags() before calling do_pci_enable_device() may > > not work. For example, if the given PCI device depends on an ACPI > > power resource whose _STA method initially returns 0 ("off"), but the > > config space of the PCI device is accessible and the power state > > retrieved from the PCI_PM_CTRL register is D0, the current_state > > field in the struct pci_dev representing that device will get out of > > sync with the power.state of its ACPI companion object and that will > > lead to power management issues going forward. > > > > To avoid such issues, make pci_enable_device_flags() call > > pci_update_current_state() which takes ACPI device power management > > into account, if present, to retrieve the current power state of the > > device. > > > > Link: https://lore.kernel.org/lkml/20210314000439.3138941-1-luzmaximilian@gmail.com/ > > Reported-by: Maximilian Luz <luzmaximilian@gmail.com> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > --- > > > > Hi Maximilian, > > > > Because commit 4514d991d992 ("PCI: PM: Do not read power state in > > pci_enable_device_flags()"), the issue addressed by it is back, so > > we need an alternative way to address it. > > > > Can you please check if this patch makes that issue go away? > > Hi, > > just tested this on v5.13 and it works, thanks! Feel free to add > > Tested-by: Maximilian Luz <luzmaximilian@gmail.com> Thank you!
On Fri, Jul 9, 2021 at 1:21 PM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Thu, Jul 8, 2021 at 10:34 PM Maximilian Luz <luzmaximilian@gmail.com> wrote: > > > > On 7/8/21 3:25 PM, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > > > Updating the current_state field of struct pci_dev the way it is done > > > in pci_enable_device_flags() before calling do_pci_enable_device() may > > > not work. For example, if the given PCI device depends on an ACPI > > > power resource whose _STA method initially returns 0 ("off"), but the > > > config space of the PCI device is accessible and the power state > > > retrieved from the PCI_PM_CTRL register is D0, the current_state > > > field in the struct pci_dev representing that device will get out of > > > sync with the power.state of its ACPI companion object and that will > > > lead to power management issues going forward. > > > > > > To avoid such issues, make pci_enable_device_flags() call > > > pci_update_current_state() which takes ACPI device power management > > > into account, if present, to retrieve the current power state of the > > > device. > > > > > > Link: https://lore.kernel.org/lkml/20210314000439.3138941-1-luzmaximilian@gmail.com/ > > > Reported-by: Maximilian Luz <luzmaximilian@gmail.com> > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > --- > > > > > > Hi Maximilian, > > > > > > Because commit 4514d991d992 ("PCI: PM: Do not read power state in > > > pci_enable_device_flags()"), the issue addressed by it is back, so > > > we need an alternative way to address it. > > > > > > Can you please check if this patch makes that issue go away? > > > > Hi, > > > > just tested this on v5.13 and it works, thanks! Feel free to add > > > > Tested-by: Maximilian Luz <luzmaximilian@gmail.com> Michael, Salvatore, since this alternative to commit 4514d991d992 works for Maximilian, I'm going to queue it up for 5.15 (barring any objections from Bjorn), so I would appreciate it if you could test it and let me know whether or not there were any problems with it. The patch can be downloaded from https://patchwork.kernel.org/project/linux-pm/patch/4327888.LvFx2qVVIh@kreacher Thanks!
On Mon, Jul 12, 2021 at 5:30 PM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Fri, Jul 9, 2021 at 1:21 PM Rafael J. Wysocki <rafael@kernel.org> wrote: > > > > On Thu, Jul 8, 2021 at 10:34 PM Maximilian Luz <luzmaximilian@gmail.com> wrote: > > > > > > On 7/8/21 3:25 PM, Rafael J. Wysocki wrote: > > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > > > > > Updating the current_state field of struct pci_dev the way it is done > > > > in pci_enable_device_flags() before calling do_pci_enable_device() may > > > > not work. For example, if the given PCI device depends on an ACPI > > > > power resource whose _STA method initially returns 0 ("off"), but the > > > > config space of the PCI device is accessible and the power state > > > > retrieved from the PCI_PM_CTRL register is D0, the current_state > > > > field in the struct pci_dev representing that device will get out of > > > > sync with the power.state of its ACPI companion object and that will > > > > lead to power management issues going forward. > > > > > > > > To avoid such issues, make pci_enable_device_flags() call > > > > pci_update_current_state() which takes ACPI device power management > > > > into account, if present, to retrieve the current power state of the > > > > device. > > > > > > > > Link: https://lore.kernel.org/lkml/20210314000439.3138941-1-luzmaximilian@gmail.com/ > > > > Reported-by: Maximilian Luz <luzmaximilian@gmail.com> > > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > --- > > > > > > > > Hi Maximilian, > > > > > > > > Because commit 4514d991d992 ("PCI: PM: Do not read power state in > > > > pci_enable_device_flags()"), the issue addressed by it is back, so > > > > we need an alternative way to address it. > > > > > > > > Can you please check if this patch makes that issue go away? > > > > > > Hi, > > > > > > just tested this on v5.13 and it works, thanks! Feel free to add > > > > > > Tested-by: Maximilian Luz <luzmaximilian@gmail.com> Gmail decided to drop Salvatore's address from the To list for me, sorry about that. > Michael, Salvatore, since this alternative to commit 4514d991d992 > works for Maximilian, I'm going to queue it up for 5.15 (barring any > objections from Bjorn), so I would appreciate it if you could test it > and let me know whether or not there were any problems with it. > > The patch can be downloaded from > https://patchwork.kernel.org/project/linux-pm/patch/4327888.LvFx2qVVIh@kreacher > > Thanks!
Index: linux-pm/drivers/pci/pci.c =================================================================== --- linux-pm.orig/drivers/pci/pci.c +++ linux-pm/drivers/pci/pci.c @@ -1906,11 +1906,7 @@ static int pci_enable_device_flags(struc * so that things like MSI message writing will behave as expected * (e.g. if the device really is in D0 at enable time). */ - if (dev->pm_cap) { - u16 pmcsr; - pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); - dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK); - } + pci_update_current_state(dev, dev->current_state); if (atomic_inc_return(&dev->enable_cnt) > 1) return 0; /* already enabled */